They don't like it when you exhibit any kind of masculine personality trait or wear more masculine things. It doesn't matter how good you look or comfortable you are, not identifying your gender as 100% female 100% of the time is apparently just going to be unattractive.

Also, being too smart is a detriment. Not all guys like airheads, but they don't like it when you're smarter than them or know more than them about a "guy" subject, like football or cars or something.

But then, if I were to go exclusively by my own experience, I'm ugly to men. So just be the complete opposite of me. And if you're like me, don't be yourself. I just wish it were that simple.